1. Field of the Invention
This invent ion relates to blended compositions containing coconut coir pith and peat moss and to processes for producing such blended compositions. More particularly, it relates to coconut coir pith and peat moss blends which are compressed for sale as baled products capable of subsequent decompression to form fluffed plant growth media demonstrating improved fluffed yield characteristics and enhanced wettability as compared with the results obtained with coconut coir pith or peat moss individually.
2. Description of Related Art
Coconut coir pith is a by-product of the coconut husk fiber processing industry. Coir is the name given to the fibrous material that constitutes the thick mesocarp (middle layer) of the coconut fruit (Cocos nucifera). In processing, the long fibers of coir are extracted from the coconut husk for use in the manufacture of brushes, upholstery stuffing, filters, twine and like products. The short fibers (2 mm or less) and dust (collectively referred to herein as "pith") traditionally have accumulated as a waste product in large piles or "dumps" outside the mills that have processed the coconut husks for the industrially valuable long fibers. The coconut coir pith has a high lignin to cellulose content which prevents oxidation and resultant shrinkage. Accordingly, these materials do not decompose rapidly, resulting in the dumps of material which have remained as accumulated waste for extended periods of time with essentially no industrial applicability other than for burning.
Relatively recently, it has been recognized that coconut coir pith material provides an excellent growing medium for plants and it has been suggested that coconut coir pith could provide an effective alternative to previously standard growing media such as peat moss. Coconut coir pith is very similar to sphagnum peat moss in appearance having a light to dark brown color and consisting primarily of particles in the size range of 0.2-2.0 mm (75-90%). Unlike sphagnum peat, however, there are no sticks or extraneous matter in the coconut coir pith. Furthermore, sphagnum peat moss has a density of about 7 lbs/cu ft when fluffed (30-50% moisture content) whereas coir pith is much denser (i.e., about 43 lbs/cu ft when compressed at a ratio of 5:1 on volume to volume basis and about 25 lbs/cu ft when fluffed and having a 50-55% moisture content).
Additional analysis of coconut coir pith in comparison with sedge peat (also known as "Florida" peat) and sphagnum peat products has indicated that coconut coir pith has superior structural stability because of the high lignin to cellulose content of the pith which prevents oxidation and shrinkage as compared with peat moss which has a high cellulose to lignin content.
Coconut coir pith to be used as a plant growth medium is prepared by collecting aged pith from existing waste dumps or newly processed pith and drying the material to a 20% moisture content and then compressing the pith into bricks at a compression ratio of about 5:1 (v/v). These compressed bricks can then be expanded by adding water to achieve yields of about 7 volumes to each 1 volume input material at about 80% moisture content although some mechanical agitation is required in order to increase the output of the outturned coir pith. This mechanical agitation requirement presents a disadvantage in processing coir pith since it results in an inconvenience and expense for many growers and other end users of the product. A further disadvantage in the processing of coir pith as a plant growth medium is that, unlike compressed bales of peat moss which can be readily fluffed or outturned to yield a desirable fluffed product, coir pith takes considerably more time to be fluffed or "outturned".
Peat moss, including hypnum as well as sphagnum peat and sedge or "Florida" peat and the like, is a product of wetland ecosystems and is harvested in relatively large quantities to satisfy horticultural demand as a plant growth medium. Sphagnum peat is harvested by harrowing the peat from bogs and swamps, allowing the harvested product to dry and vacuum collecting it. Then, the peat moss is screened and baled. Compression ratios when baling the peat range from 1.5:1 to 2.5:1 (v/v) with an average of about 2.0:1. It is known that compression ratios below about 1.5:1 are economically unacceptable and that higher compression ratios would be commercially significant.
However, a disadvantage in the processing of peat moss for use as a plant growth medium arises as a result of the fact that compression ratios greater than about 2.5:1 cannot practically be applied to baled peat products since such ratios result in fiber destruction of the peat and consequently low fluff yields and poor product performance.
A further disadvantage in using a natural resource such as peat moss is that at the levels at which it is harvested to satisfy the substantial horticultural demand, it really cannot be considered to be renewable. Consequently, a high quality alternative to peat moss that is consistently available and also satisfies heightened environmental concerns has been recognized heretofore as being a desirable objective, and that it would be environmentally beneficial to decrease the amount of harvested peat required for horticultural use.
Another problem that has been encountered with peat moss is that when bales of this material are allowed to stand for a prolonged period of time prior to use (e.g., greater than 12 months), the peat fibers dry and become brittle resulting in reduced fluffed yield. Also, it is well known that sphagnum peat is hydrophobic and requires addition of moisture and wetting agents to cause it to take on water quickly. Coir pith, on the other hand, takes on water rapidly even at low moisture levels and without addition of any wetting agents. This rapid wetting of coir pith occurs even after wet/dry cycles; whereas when peat dries after wetting, it is quite difficult to rehydrate the product.
Another characteristic of coir pith which is distinguishable from peat moss is that coir pith is granular in nature and holds water in a matrix equivalent to a "honeycomb" or sponge, whereas peat is fibrous in nature and does not retain moisture as readily. Thus, coir pith does not shrink as much as peat moss and peat moss does not wet as well as coir pith. Furthermore, coir pith has a higher lignin/cellulose content than peat moss so that peat microbially degrades faster than coir pith, which causes weakening of the fibers and results in "shrinkage".
Thus, it was suggested that coconut coir pith could be a viable alternative to peat moss as a growing medium. However, certain problems have been recognized in regard to the economic and operational suitability of coir pith in such horticultural applications including, for example, the processing disadvantages noted above in regard to the production of coir products. It was recognized in the art that it would be advantageous to improve the usage yields, after compression and fluffing, of bags of plant growth media containing peat moss so as to conserve this natural resource.
Accordingly, products were developed which include mixtures of coir pith and peat moss. These products are now commercially available and are produced from compressed bricks of coir pith and bales of sphagnum peat moss which initially are decompressed to provide separate fluffed coir pith and fluffed peat moss raw materials. Then, the already fluffed materials are mixed together for outturning and packaging for distribution as a "loose-fill" product containing the decompressed, fluffed mixture of coir pith and peat moss. The fluffed products produced in this manner have been demonstrated to provide better media for growing plants than the media provided by coir pith or peat moss alone. It is believed that this improvement results from the peat fibers holding the coir pith granules together to provide for a more stable rooting environment. Furthermore, coir pith has been found to alleviate or reduce the disadvantageously poor wetting provided by the peat moss alone and, also, to reduce shrinkage of the peat moss. However, it has been recognized previously that these "loose-fill" products are not advantageous for purposes of shipment and/or storage of the products and that more favorable methods for producing growing media containing these mixtures would be commercially significant. It has been a source of continuing investigation to provide methods for achieving enhanced fluffed yields of blended compositions of coir pith and peat moss and for enabling the production of compressed mixtures of coir pith and peat moss which has not been possible heretofore.